I'm very new to pipe making and have done few experiments and keyed prototypes. I'm wondering how you calculate the tone hole placement on the chanter, I haven't seen any information about this. Is there a specific formula or other method used for placing tone holes?

I've done some research into acoustic physics and went as far as to create a calculator based off of some equations used for flutes. It seems to give good results but judging from pictures (never seen a set in person ) I'm not sure how correct my results are. For example the high b (highest keyed hole) in a G set with a 4.3mm bore would be placed at a distance of about 81mm (little over 3 inches) from the point where the air stream splits (somewhere in the reed). I'm ordering some new steel to make a bore drill with so I haven't been able to test my results.

Furthermore, I've seen the wealth of information on Mike's machine concepts page. I noticed that the chanter drawings are marked as "unchecked." Has anyone made the 7-keyed concert G chanter from his drawings?

I have based my hole positions on the work of Colin Ross. I have made a few tweaks but nothing much.

It would be really useful if some other pipemakers posted their dimensions so that we could see how they compare.

One thing to consider is that finding a perfect hole position will always be a compromise. I aim to have the drilled hole set a bit flat so that I can undercut it towards the reed as that seems to give a better tone.

After some research on Colin Ross it seems best to make pipes that follow his design, and looks like he set the standard on hole spacing. It's looking to me that hole placement is something that's copied from one maker to the next. Mathematically I think the closed fingering and closed-end pipe throw common formulas out the window. Starting the notes flat is a good thing to remember, especially if undercutting improves the tone.

I think its fair to say that hole spacings are copied from one maker to another - sometimes with intelligent interpretation. Whilst there is no standard, the variations can mostly be attributed to differences in reed design. I have a spreadsheet with a number of makers' spacings on, for "F" pipes, ranging in time from Reid to Ross and covering all the makers I could easily find examples to measure. With historical pipes one cannot always tell whether the holes have been altered or modified from the original, of course.

I haven't done the same for G pipes. The first G chanter was made in the early 1960s: but was made to take an F reed. Subsequent makers have modified the reed and I suspect the hole positions would be more widely various than they are on F pipes where pitch varies from the concert F favoured by some makers, through "F+" to F#.